Michelle Obama succeeded last night in her opening-night audition for the role of first lady. She was poised and open, humble and forthcoming, patriotic, and above all a champion for her husband. I disagree with my friend Mike Tomasky - schmaltz on Michelle Obama would smell false, and what the audience was looking for was genuine sentiment. Sell it too hard and you lose us – this is not a woman who normally gets treacly and weepy. If she'd tap-danced too hard about patriotism, I wouldn't have bought it, and neither would have America.

Obama's task last night – made infinitely more difficult by the relentless coverage of her "proud" gaffe some months back – was to define herself and her marriage not outside of race but not entirely defined by it either. You could hear it in the moment early on in her speech when she called herself first a "sister" and there was a beat, small but noticeable, before she went on to talk about her relationship to her impressive biological brother. But of course Michelle is also a "sister" in the African-American sense, and I'm quite sure that pause, that nod, did not go unnoticed in the wider audience.

But beyond that split-second, and an applause line for the 45th anniversary of when "Dr King lifted our sights and our hearts with his dream for our nation", the emphasis of Obama's text was on countrywide wholeness - not about racial separation or the efforts of men and women of colour in an ongoing battle for a united country, but about universal struggles.

Dr King was mentioned in the same breath as the battle for women's suffrage, and both of those historic struggles were wrapped up in a package that addressed all working men and women, black and white, red state and blue state. This was a speech that was the child of senator Obama's historic Democratic convention address in Boston in 2004. Just listen to how she went on:

I stand here today at the crosscurrents of that history - knowing that my piece of the American Dream is a blessing hard won by those who came before me. All of them driven by the same conviction that drove my dad to get up an hour early each day to painstakingly dress himself for work. The same conviction that drives the men and women I've met all across this country.

The other day a prominent German journalist commented to me that he believed the reason President Bush's tremendous lack of public support hadn't had a negative impact on McCain was almost entirely based on racism. Americans, he mused, are still unclear about a black president. That's why, he said, Barack Obama had failed to pull ahead of McCain in the polls. A random white politician would have done better.

While I find that summation of the close polls too simplistic, the dance of racial recognition and ultimate transcendence was certainly on stage last night. Patriotism sold any harder than Michelle Obama's crescendo simply wouldn't have worked:

All of us driven by a simple belief that the world as it is just won't do - that we have an obligation to fight for the world as it should be. That is the thread that connects our hearts. That is the thread that runs through my journey and Barack's journey and so many other improbable journeys that have brought us here tonight, where the current of history meets this new tide of hope. That is why I love this country.

This is her patriotism. It might not be enough for everyone, but I was sold.

Patriotism as defined by Michelle Obama was about a unified vision of the country, a unified struggle. She didn't need to say she sits beside her children when they are sick, or stands behind her husband when he runs for office. It was clear.

It helped her cause that nothing looked more like Camelot than Sasha and Malia Obama - so clearly in love with their parents - coming out to greet their mom, poised in her turquoise dress. And that nothing sounded more normal, as Noam Scheiber at the New Republic pointed out late in the evening, than a brother vetting a boyfriend by basketball, or a father dressing slowly to overcome his encroaching disease but refusing to give up the honour and privilege of raising a family.

The Obamas have been all about revealing the normalcy of non-whiteness from the beginning of this campaign, and nothing could have been more normal than Michelle Obama's narrative in Denver.

Last night Michelle Obama was a "mom" and a "daughter" and a "wife" and an American. Well-layered beneath those wholesome titles came her credentials as a lawyer, a working woman, a success in her own right. This was a first-class bid to be first lady.

Michelle Obama understands, whether she likes it or not, what is required of her in the run for the White House and the office of the first lady. Last night she met those expectations with aplomb.